A Japanese theme park where youve got to be in the nude

There aren’t nearly enough theme parks in the world where you can get naked ­– but leave it to Japan to right this terrible wrong.

Osaka’s Spa World amusement park, dedicated to the Japanese love of soaking one’s cares away, is not for the timid traveller – or the tattooed one, but more on that in a moment.

Set in the largest building of the somewhat dodgy Shinsekai area, this wellness-filled behemoth offers eight levels of hot baths, hot tubs, foot baths, rock beds, steam rooms and hammams.

There's also massages, a gym, a formal hotel plus informal resting areas, snacks and that food court (it takes supreme self-confidence to down a burger and fries during a naked stint with total strangers, but good luck to you).

Of course, the nudity only happens here once the genders are separate. The fourth floor is the European zone, the sixth floor the Asian zone, and women use one, and men the other – Spa World alternates usage depending on the month, so check the website to see where you’ll end up.

The Finland sauna house and the salt area in the European zone are always favourites. All of these areas are not just clothing-optional – nudity is compulsory.

However, the colourful family-friendly pool on the top floor with multiple, rather hardcore waterslides snaking through the air above it is mixed-gender and thus swimsuited.

You can rent swimsuits for the fun pool, if you’re caught short, and the waterslides also cost extra. Your second wristband comes with your locker key.

But it's important to understand the very structured etiquette involved in enjoying Japanese cultural favourite, the onsen or hot spa bath.

Considering, at a basic level, it’s a body of hot, still water with no soap, chlorine or other additives to keep it clean, and you’re sharing it with a steady stream of strangers, the rules do make sense.

No clothes – not even bathing suits – is the first and foremost rule (tie up your hair, too).

Have a wash in the allotted area, squatting on a stool, then leave everything including your washcloth behind, to have a soak in the waters.

Once you’re feeling all soft and squidgy, get out for a proper wash to really scrub yourself clean. Once you’re rinsed again, time for more onsen for an even deeper relax.

This is where things get sticky for anyone sporting tattoos. Any tattoos at all. Spa World bans anybody "related to crime syndicate", and tattoos are a sign of the Yakuza.

No, they don’t care that you are a Westerner and therefore not likely to be Yakuza.

No, you can’t cover it in sports tape. No, it doesn’t matter that it is a tiny centimetre-high Mickey Mouse.

A few punters have successfully ducked the system, but avoid the embarrassment and go to the aquarium instead.

There are also plenty of hotels with private onsen, if you want the experience.

If you are tattoo free and confident in body, then the whole package is well worthy of a generous half-day (or night) to try a little bit of everything.

Once you get past the muscular faux Greco-Roman statuary at the entrance, pay your entry fee ($35–$38 for all-day use) and get your first wristband – this one gets scanned, once you’ve gone au naturel, for any purchases such as food, drink, massages, hot rock beds or souvenirs.

And then its time to just enjoy the onsen on steroids known as Spa World.